One or more wind turbines may be connected to a point of common coupling (PCC) which in turn is connected to a utility grid to provide electric energy to plural consumers.
Normally, the short circuit capacity at the point of common coupling is used to determine the strength of grid. When wind farm is located close to the main generation units where the short circuit capacity is high, it is said that wind farm is connected to a strong grid. However, in some situations, the wind farm is located far from the main generation units the short circuit capacity is low, it is said that wind farm is connected to a weak grid. In other situations, a strong grid is changed into a weak grid due to fault, for example, trap of transmission lines.
It has been observed that with a conventional method and arrangement in a wind turbine controller, it might not be able to obtain similar or stable responses at least of some electrical properties for both weak and strong grid.
There may be a need for a method and arrangement for operating a wind turbine in both strong grid and weak grid, especially in a weak grid which is connected to a utility grid, wherein electrical requirements, in particular at the wind turbine and/or at point of common coupling, are satisfied. Further, there may be a need for a method and an arrangement for controlling a wind turbine, in particular for adjusting an output voltage of the wind turbine to a reference value.